‘We are encouraging people to look around their attic and find out if they have a connection to the service they didn’t know about before.

‘You never know what might crop up. If people find service papers and memorabilia, we can help them make sense of it. More often than not, you will find out about someone you never realised was in the service.’

The latest exhibition features interesting artefacts not normally on display in the museum and has expert advice for people attempting to trace their ancestors.

Visitors can leave their details at the museum so archivists can check if they had a relative in the marines.

Mr Little said: ‘Marines have been around since their start as sea soldiers in 1664.

‘It’s likely many people living around Portsmouth have had someone in their family history who’s served as a marine at some point.’

The museum on the seafront in Eastney has invested a large chunk of a £50,000 Heritage Lottery grant upgrading its archive storage, which includes new rolling shelves to hold the 1.5m artefacts, photos and documents in its possession.

It is the first time the entire museum’s archive has been rehoused since 1958.

In the coming years, archivists aim to scan in and take pictures of all its stock to create a digital archive on the internet which can be accessed around the globe.

The project will include facial recognition technology applied to photos so researchers can put names to faces with a click of a button.

‘It’s an exciting project,’ said Mr Little, who has worked as an archivist at the Royal Marines Museum for 34 years.

He added: ‘Genealogy is a growth industry and we hope people get involved in uncovering the thousands of untold stories that are out there.

‘We are interested in people doing that research so we can add them to our growing database of people we can use for our future exhibitions.’